Number of GABA immunonegative and GABA immunopositive neurons in human epileptic temporal cortex.

The number of neurons, both GABA immunopositive and immunonegative, was determined in temporal epileptic foci of 7 patients after temporal lobectomy, and compared to neuronal numbers in temporal cortex of two controls taken from tumor operated patients. The thickness of the cortex of the epileptic cortex diminished by about 10%, while the number of nerve cells decreased to 67% of that of the control value: it was 19.000/mm(3) vs. 28.000/mm(3) found in the control. This decline was due to cell degeneration, which, however, was more severe for non-GABAergic nerve cells. Accordingly, the proportion of the GABA-positive neurons in the otherwise diminished neuronal population increased to 36.4% from the 32% control value. The number of GABAergic terminals, however, decreased even further, explaining the resulting disinhibition during epileptic seizures.